SQL Server Performance

Smaller Disks-More Spindles

Discussion in 'SQL Server 2005 Performance Tuning for Hardware' started by DavidDay22, Aug 6, 2007.

  1. DavidDay22 New Member

    I am beginning to get the message, that more disks are better. I have a Dell Poweredge 2850 hooked up with a PERC4/DC to a Powervault 220 with 146 GB 15k drives. Is there a maximum number of disk where performance drops off? I am thinking if I add a PERC4e with a MD1000, with 15 73 GB disks, I can increase the performance. Which array do I put the logs on and which do I put the data on?
  2. satya Moderator

    I don't think so, that is not correct it purely depends upon the transactions method & when the CHECKPOINT is issued on the database.
    Have you used SYSMON to capture disk related counters for analysis.
  3. DavidDay22 New Member

    From PERFMON the biggest problem I see is Physical Disk Avg. Disk sec/Read _Total is running sustained at 0.016.
  4. satya Moderator

    I'm going into basics again just to re-visits few things we miss always, some disks and disk configurations perform better when reading than when writing. You can compare the reading and writing capabilities of your disks by reading from a physical disk and then writing to the same physical disk. You might see some variations in the time it takes to read from or write to disk on standard disk configurations, also when you start writing to the disk during a read operation that you are monitoring, you will notice some dips in the curves of graphed data for read activity. This is because the application doing the reads must stop briefly to allow the write operation to proceed and then, when the write is finished, the read operation resumes. You can observe this as Performance Logs and Alerts service logs data.
    If your configuration contains different types of disks, controllers, and buses, the differences in their designs can have an influence on throughput rates. You might want to test throughput using these different disk systems to determine if some components produce less favorable results overall or for certain types of activity, and replace those components as needed. Be aware of the seek time, rotational speed, access time, and the data transfer rate of your disks by consulting manufacturer documentation. Also consider the bandwidth of cabling and controllers. The slowest component determines the maximum possible throughput, so be sure to monitor each component.

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